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Auto-changeover Electronic Thermostat
2 Heat/2 Cool, Auto or Manual Changeover, Hardwired
Part No. 668375401
For replacement parts call 1-800-377-2787
©2008 McQuay International • www.mcquay.com • 800-432-1342
Installation & Operation Manual
● Configurable
● Two Stage Heat / 2 Stage Cool Systems
● Backlit Display
● Field Temperature Calibration
● Status Indicator Light
● Relay Outputs (minimum voltage drop in thermostat)
● Night Set-Back Override
● Reset
LIA266
Group: WSHP
Supercedes: LIA204-4
Date: May 2007
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Table of Contents
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Summary of Contents for McQuay LIA266
- Page 1 Auto-changeover Electronic Thermostat 2 Heat/2 Cool, Auto or Manual Changeover, Hardwired Part No. 668375401 ● Configurable ● Two Stage Heat / 2 Stage Cool Systems ● Backlit Display ● Field Temperature Calibration ● Status Indicator Light ● Relay Outputs (minimum voltage drop in thermostat) ● Night Set-Back Override ● Reset For replacement parts call 1-800-377-2787 ©2008 McQuay International • www.mcquay.com • 800-432-1342...
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Page 2: Table Of Contents
Table of Contents Parts Diagram ..........................1 Specifications ..........................2 Important Safety Information .....................2 Package Contents/Tools Required ....................2 To Remove Existing Thermostat ....................3 To Install Thermostat ........................3 Remote Sensor Installation (Optional) ..................5 Terminal Designator Descriptions....................6 Wiring Diagrams ..........................6 Configuration Mode ........................8 Testing the Thermostat ......................11 Mode of Operation ........................12 Operating Modes ........................13 Troubleshooting ........................14... -
Page 3: Parts Diagram
Parts Diagram 668375401 W1 Y1 W2... -
Page 4: Specifications
Specifications Electrical rating: • 24 VAC/VDC (18-30 VAC/VDC) • 4 amp maximum total load • 1 amp maximum per terminal Temperature control range: 45°F to 90°F (7°C to 32°C) Accuracy: ± 1°F (± 0.5°C) System configurations: 2-stage heat, 2-stage cool Timing: Backlight Operation: 13 seconds after mode change or button press Terminations: -C, +R, W1, Y1, W2, Y2, G, O, S1, S2 Important Safety Information WARNING!: Always turn off power at the main power supply before installing, cleaning, or removing... -
Page 5: To Remove Existing Thermostat
To Remove Existing Thermostat ELECTRICAL SHOCK HAZARD – Turn off power at the main service panel by removing the fuse or switching the appropriate circuit breaker to the OFF position before removing the existing thermostat. 1. Turn off power to the heating and cooling system by removing the fuse or switching the appropriate circuit breaker off. - Page 6 To Install Thermostat (continued) To remove cover, insert and twist a coin or screwdriver in the slots on the sides of the thermostat. Put thermostat base against the wall where you plan to mount it (Be sure wires will feed through the wire opening in the base of the thermostat).
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Page 7: Remote Sensor Installation (Optional)
Remote Sensor Installation (Optional) Requires McQuay Remote Sensor Part Number 667720401 1. Remove cover from remote sensor housing. 2. Select an appropriate location for mounting the remote sensor. 3. Mount remote sensor unit using hardware provided. 4. Install two strand shielded wire between remote sensor and thermostat. Shielded wire must be used. -
Page 8: Terminal Designator Descriptions
+R – 24 VAC/VDC hot W1 – 1st stage heat Y1 – 1st stage cool W2 – 2nd stage heat Y2 – 2nd stage cooling G – Fan O – Override Wiring Diagrams McQUAY SINGLE CIRCUIT ELECTRONIC THERMOSTAT Override (Optional) - Page 9 McQUAY DUAL CIRCUIT ELECTRONIC THERMOSTAT Override (Optional)
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Page 10: Configuration Mode
To configure the McQuay Auto-changeover Electronic Thermostat, perform the following steps: 1. Remove the cover of the thermostat by gently pulling on one of the corners. 2. Simultaneously hold the SW5 and SW6 buttons in for 5 seconds while the McQuay Auto-changeover Electronic Thermostat is in OFF mode. - Page 11 4. 1 Stage Temperature Differential (1°F to 3°F) (0.5°C to 1.5°C) REMOTE REMOTE Set the number of degrees between your “setpoint” temperature ROOM ROOM and your “turn on” temperature. DIFF DIFF Press the button to set differential value. FILTER FILTER Press the SW6 button to advance to the next screen. 5.
- Page 12 Maximum Heat Setpoint (55°F to 90°F) (13°C to 32°C) REMOTE REMOTE Adjust to control the maximum Heat set temperature allowed. ROOM ROOM Press the button to select. DIFF DIFF Press the SW6 button to advance to the next screen. FILTER FILTER 10. Room temperature offset (+9°F to -9°F) (+4.5°C to -4.5°C) REMOTE Adjust to calibrate displayed room temperature to match actual room temperature.
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Page 13: Testing The Thermostat
Testing the Thermostat Once the thermostat is installed, it should be thoroughly tested. CAUTION!: Do not energize the air conditioning system when the outdoor temperature is below 50 degrees. It can result in equipment damage or personal injury. Cool Test 1. Slide Mode switch to Cool mode. 2. Adjust set temperature so it is 5 degrees below room temperature. 3. Air conditioning should come on within a few seconds. Status indicator may come on. 4. -
Page 14: Mode Of Operation
Mode of Operation The McQuay is a two-stage heat, two-stage cool thermostat. Auto-changeover Electronic Thermostat The thermostat activates the first stage of heating when the room temperature is below the heat set temperature (by the differential temperature). The second stage of heating will be activated if the room temperature continues to drop. -
Page 15: Operating Modes
Operating Modes These are the possible operating modes of the McQuay Auto-changeover Electronic Thermostat Off Mode In off mode, the thermostat will not turn on the heating or cooling appliances. Note 1: The indoor fan can be activated in every mode by sliding the Auto/On fan switch to the On position. -
Page 16: Troubleshooting
Troubleshooting Symptom Remedy No display Check for 24 VAC/VDC at thermostat; display is blank when 24 VAC/VDC is not present System fan does not come Verify wiring is correct on properly Check configuration (see “Configuration Mode,” Setting 2, Page 8) See “Fan Test”... -
Page 17: Factory Default Settings
McQuay Auto-changeover Electronic Thermostat Factory Default Settings Note: Following are the factory default settings for the McQuay 2811 thermostat: Heat pump HS gE Differential 01 Differential 02 Staged outputs Calibration Maximum compressor cycles per hour... - Page 18 This page left intentionally blank.
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- Page 20 Now that you have made an investment in modern, efficient McQuay equipment, its care should be a high priority. For training information on all McQuay HVAC products, please visit us at www.mcquay.com and click on training, or call 540-248-9646 and ask for the Training Department.
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